Method of cleaning fabrics



Patented May 30, 1933 UNITED STATES PATENT OFFICE WARREN T. REDDISH, OF CINCINNATI, OHIO, ASSIGNOIR- TO EMERY INDUSTRIES, INC., OF CINCINNATI, OHIO, A CORPORATION OF OHIO METHOD OF CLEANING FABRICS No Drawing.

This invention relates to a new art, method, and process of cleaning garments, fabrics, textiles, cloth, rugs and articles of like na ture which, for the sake of convenience, throughout the remainder of the description, will be designated by the term fabrics unless otherwise specifically identified.

In view of the fact that the invention lends itself to being practiced in so-called dry cleaning establishments, on the classes of articles usually cleaned there and with the types of equipment usually used there, the present invention is described and cla1 med as an improvement in the dry cleamng art. However, the physical chemistry utilized in practicing this invention and the results obtained, are so contrary to the pr nciples and go so far beyond results now deslgnated by the term dry cleaning, that one might classify the fabric cleaning develop-' ment of this invention as an entirely new art. In order to comprehend the true novelty of principle of this invention, a brief review of the theories of previously known methods of cleaning fabrics is requisite. Cleaning fabrics has been accomplished 1n the past either by a soap and water process or by the dry cleaning process. The dry cleaning process differs in principle from the wet washing process. In the wet washing process the dirt part1- cles on the fabric are removed by emulsification and saponification of the oils and greases which bind the particles to the fabric. This is usually accomplished by washing the fabrics with the ordinary fatty acid soaps wh ch possess emulsifying powers in water solution and liberate alkali by hydrolysis whlch combines with the saponifiable oils present. Those fattv acid soaps also lower the surface tension of the solution which accelerates the detergent action by increasing the rate of penetration of the soap and water into the fabric. The highly water soluble soil which may also be present is removed, of course, by the solvent action of the water. This process is injurious to a majority of types of fab- Application filed February 4, 1932. Ser'al No. 590,981.

invention is directed, a conventional cleaning solvent is employed of the type exemplified by a volatile hydrocarbon or chlorinated hydrocarbon, the more commonly used of which are gasoline, naphtha, carbon tetrachloride and trichlorethylene. At present, the dry cleaning process is usually practiced by treating the fabrics in rotating drum type washers containing the cleaning solvent to which may be added suitable so-called dry cleaning soaps which decrease static and lower surface tension. The agitation is continued for from ten to thirty minutes, depending upon the type of fabrics being treated and their. condition.' During this treatment, the oily or greasy film, which binds the dirt particles to the fabrics, is dissolved and the dirt particles are removed by the agitation of the fabrics in the solvent. The articles are then rinsed in clean solvent and cent'rifugally extracted and then dried either in rotary drum type dryers or in heated rooms. By this treatment oily and greasy soil is removed without shrinkage of the fabric or damage to. the sizing and finishing materials, the dyes or the fibre itself.-

However, marks or disfigurations called water spots which are caused by water having come in contact with the fabric and roughened or partially dissolved the finishing material and spots caused by solely water soluble substances, such as perspiration, soft drinks, sugar syrups, and the like, are not removed by this process. It is, therefore, nec

essary to employ water or other suitable solvents to remove them. This is usually done by hand spotting of the affected local areas in order that the amount of water coming in contact with the fabric may be kept down to a minimum; Due to the labor involved, this operation is relatively expensive compared to the rest of the'process. Moreover, the results obtained depend upon the skill of the worker and, at best, are highly unsatisfactory.

Such spots may in some cases be removed by what is called the wet-dry treatment in ric because it often causes shrinkage, fading/ which the fabric is first immersed in the or disfiguration. v In the dry cleaning industry tOWhlCll this cleaning solvent and then, while still saturated with solven t, treated with'cold water or a dilute soap solution for from three to five minutes. The presence of the cleaning solvent in the fabric prevents the absorption of sufiicient water to cause appreciable shrinking, loss of sizing material or bleeding of colors, but allows the water to come in contact vwith the soluble spots sufficiently to bring This process is tedious, expensive, and may injure a fabric or fail to remove the spots, or both. Obviously, both hand spotting and the wet-dry methods are make-shifts dependent upon artizan skill and judgment. It is, therefore, to be observed at this point that there is no existing process for cleaning fabrics which is inherently adapted to be used on all types of fabrics to remove all types of soil.

It hasalways been customary (and still is) to clean fabrics made from vegetable fibres such as cotton and linen goods, by washing in soap and water. This process can also be used on some articles of wool, silk and rayon, but very great care is required, and generally speaking, the fabrics made from fibre of animal or synthetic origin, which are adapted to the soap and water washing process, are the exception rather than the rule.

Most of the outer garments worn in this country at present, such as suits, dresses,

about their solution.

coats, etc., are made from fibres of animal origin, usually silk or wool, or both. Such articles are ruined in appearance by soap and water washing. As a result of the development of cheap cleaning solvents in the last half of the last century, and as a result of the shifting of population to the large urban centers in which more formal attire prevails, the central dry cleaning plant came into being and its facilities became widely available.

The ubiquity of the dry cleaning plants permitted the designers of fabrics to develop a great many new sizing and finishing materials, special weaves, peculiar thread twists, and many new and brilliant dyestuffs, which in cleaning would require the special skill and equipment of the large central dry cleaning establishments. On this account, the so-called dry cleaning process has become a tremendous national industry despite the fact that it does not remove water marks and is inherently adapted to remove from the fabrics but one class of soil, that is, the oil soluble soil, as distinguished from perspiration and other types of water soluble soil.

The object of this invention is to provide an entirely new and novel art, method or process by means of which fabrics are cleansed of substantially all varieties of spots or soil without individual attention to each article treated or the utilization of artizan skill and judgment.

This invention resides in a series of recognitions, concepts and determinations which have required and received verification by large scale commercial operation upon all cleaning solvent to a very extreme degree, for I instance, that degree which is signified by a substantial optical clarity of the solution, then the moisture will not have its usual deleterious effects upon the fibre, the dyestufl', or the finish of the fabric being treated. In other words, even the finest silk evening dress will not be injured by this treatment.

Thus, it is possible to remove the water soluble spots or soil with a quantity of dispersed moisture which is not injurious to the fabric being treated, or vice versa, a quantity of finely dispersed moisture, so small thatit does not injure the fabric being treated, has the capacity to remove the water soluble spots andv soil. Still otherwise expressed, the invention resides in the concept and determination that an appropriate amount of moisture appropriately dispersed throughout a dry cleaning solvent, possesses the desirable cleaning properties of water but not the disadvantages.

The next feature of this invention, which is rather unexpected, is that the quantity of moisture adapted to produce the best results should be determined and controlled primarily in relation to the weight of the fabrics treated, rather than in relation to the weight or quantity of the cleaning solvent used. This is due tothe fact that the fabrics always absorb substantially all of the moisture in the cleaning solvent. Therefore, the

quantity of moisture contacted with the fabrics or transferred to the fabrics in the process, is the critical factor rather than the ratio of moisture to cleaning solvent in the bath in which the fabrics are treated. However, the amount of moisture to be used in practicing this invention must not exceed the moisture tolerance of the type of fabric being cleaned. 1

The more specific aspects of the invention may be said to reside in the determination that a useful cleaning action is obtained by agitating the fabrics in a body of cleaning solvent containing about five percent of their weight of moisture and that in many cases, the weight of moisture may be increased to thirty percent of the weight of the fabrics without injury thereto. For instance, silk garments may be cleaned by treatment with between five and fifteen percent of their weight of moisture, though approximately ous evening gowns.

ten percent is recommended for most large scale commercial runs which include numer- In the case of mens suits, ten to thirty percent of their weight of moisture may be used in the cleaning solvent, though fifteen percent seems to produce the best average results on a batch of winter suits collected from a high class suburban neighborhood.

It is obvious that if a fine satin evening dress were treated in a bath in which water and naphtha were simply churned up together, the dress would become hopelessly water spotted because of large drops of water absolutely saturating the dress in many local areas. Such an undesirable effect diminishes in proportion to the fineness of the particles of water. Even a coarse emulsion would ruin a silk dress because the emulsion would saturate completely certain local areas with water and other local areas with the naphtha. If, however, the dispersion of the moisture in the naphtha is so fine that the solution is substantially optically clear, then the absorption of moisture by the fabric being treated is-more analogous to the absorption of moisture by a fabric in a very damp climate, for instance, on the seashore.

This new process in which a fabric is treated with and takes on betweenfive and thirty percent of its weight of moisture, under normal conditions, (a large group. of fabrics being churned about in a container of cleaning solvent and moisture), results in the removal from the fabrics of water soluble soil such as syrup spots, perspiration marks,

' soft drink spots, and the like, as well as all disappear from the fabric and oily or greasy soil. Moreover, water spots many types of finish, in general use at present, seem to be not only completely restored and renovated, but improved by this treatment, so that the fabrics look as well or even better than they did when new,

In view of the fact that moisture does not admix readily with the cleaning solvents in common use at present, absorbefacients must be used( these will be described at a later point). While the moisture for the first batch of fabrics may be added to the cleaning solvent directly with the absorbefacient, it is believed to be better practice and more in conformity with the spirit of this invention first to add the absorbefacient to the cleaning solvent and thereby create in this cleaning solvent the capacity to absorb'the substantial and requisite quantities of moisture in a state sufliciently fine and dispersed as not to be injurious to the fabrics to be treated. Then the desired quantity of moisture may be determined and added for each batch of fabrics treated. This step is termed. charging the cleaning solvent.

It is recommended that the cleaning solvents be constituted water absorbent for the maximum amount of moisture requisite for the impending operations. If this be done, then it is not necessary to adjust the ratio of absorbefacient to cleaning solvent for particular or unusual conditions which may arise.

In commercial operations, each batch of fabrics to be cleaned is weighed. Generally speaking, fifty or sixty pounds of fabric are considered the maximum load for about fifty gallons of cleaning solvent. The cleaning solvent is charged with moisture, the amount being based upon the weight of fabrics being treated. In this connection, attention should be paid to the humidity of the atmosphere which normally determines the percentage of moisture already in] the fabrics. Likewise, it is necessary to take into account the nature of the fabrics being cleaned and the degree of soil.

It is obvious, of course, that fabrics afi'ected by a large amount of exclusively water soluble spots or soil, require treatment with larger quantities of moisture to effect removal than do fabrics having a small amount of soil of this type. When mens rough clothes or the like' are being treated, it is possible, if de sired, to incorporate so much moisture either before the treatment-or during the treatment, that the cleaning solvent becomes murky without injuring the fabrics, though in the case of ladies fine silk dresses and articles of like nature, injury is almost sure to occur if the dispersion or moisture be coarse. It must be remembered in this regard, that the optical properties of the solution are mentioned solely for the purpose of-indicating the degree of subdivision or dispersion of its moisture content, and that these optical properties have no merit or virtue in and of themselves. 1

In many climates and cases it is desirable to dry out the fabrics before they are treate d, as this step permits the transfer of a larger quantity of moisture to the fabric and hence provides a greater cleaning effect for a given final moisture content of the fabric in question. For instance, if silk garments are be ing treated and the final moisture content is substantially over fifteen percent, then difficultyis often experienced in the pressingroom because of wrinkling. Such garments, however, can be entirely satisfactorily cleaned and pressed first by drying them out, then treating them with about ten percent (based on the weight of the fabrics) of moisture incorporated in the cleaning solvent.

The preferred process, as a series of steps, comprises: first, drying out the fabric to be cleaned, if necessary. Next. the fabrics are weighed. Next, they are given a preliminary dip in a straight solution of cleaning solvent to get off the worst of the dirt and saturate the fibres with cleaning solvent. Next, moisture is introduced into a second batch of cleaning solvent to be used for the crucial cleaning treatment, the amount of moisture used being approximately equal to between five and thirty percent of the weight ofthe fabrics being treated. Ten percent is recommended for fine silks and fifteen percent for mens suits.

After this the fabrics are agitated and churned about in this cleaning bath for a period of between fifteen minutes and half an hour, depending upon the fabrics and their condition. It is highly desirable to filter the cleaning solvent during this cleaning process. in order to prevent dirt particles being loosely deposited upon the fabrics as they are removed from the bath. In view of the fact that most of the filters in use for this purpose do not"permit.moisture to pass through them, it is reeommendedthat this filtering be confined to approximately the last quarter of the treatment inasmuch as by that time substantially all of themoisture present has been absorbed by the fabrics being cleaned.

It is of great importance that the absorbefacients employed in the process have the capacity to pass the filters in solution. Otherwise the process would not be adapted for use in the modern. well-equipped dry cleaning plants. in practically all of which filtration during treatment is standard practice. The absorbefacient, therefore, must form in the cleaning solvent a stable, permanent, solution which will pass the filters,

will not settle out. or change chemically or physically in such wise as to lose its requisite colloidal properties.

The fabrics are next given a rinse in cleaning solvent after which they are dried and subjected to relatively routine handling. The filtration of the cleaning solvent containing the absorbefacient may be continued after the removal of the fabrics until the solvent is clarified to the desired extent. As pointed out previously. the amount of moisture added must be determined and calculated in relation to the weight and nature of the next batch of fabrics. After the cleaning solvent accumulates too great an amount of oil soluble soil or contamination to be clarified and purified by filtration, it is distilled and a new moisture absorbent solution constituted.

As far as is known, it is necessary to use absorbefacients in all of the cleaning solvents at present available to endow them With the properties requisite for the practice of this invention. These properties desirable for the cleaning solvent include: filterability (in the absence of moisture); power and capacity to repeatedly absorb substantial quantities of moisture in a state of subdivision so fine that the solution is substantially optically clear: chemical inertness towards all varieties of fibres, dyestuffs, sizes and finishes;

physical and chemical stability.

The problem of constituting such a cleaning solvent is believed to be, at present, beyond the ordinary skill of colloidal chemists, and surely beyond the skill of the dry cleaning industry. Therefore, for the purpose of assisting the skilled in the art in practicing this invention, a number of formulae for absorbefacients is provided. Claims, however, directed to the specific absorbefacients and to their physical and chemical actions, are reserved for co-pending applications inasmuch as the principles involved are susceptible to useful employment in many different arts in addition to that of cleaning fabrics. The claims in the present case are, therefore, limited entirely to the art, or method or process of cleaning fabrics herein disclosed. These formulae of absorbefacients are as follows:

Percent Connnerclal sulfonated castor 011 containing 31% water 3O Oleic acid 21 Potassium oleate 9 Water (3 Naphtlia Hexa hydro phenol Sodium salt of sulfonated oleic acid naphthalene, condensation product-neutralized Twitchell reagent 1 4 Sodium oleate Oleic acid Ethylene glycol, monobuty1-ethe|;

A 10% solution of the above formula in cleaning naphtha produces a cleaning solvent capable of containing 1% moisture. The percentageconcentration of th s absorbefacient in the cleaning solvent is critical.

Hydrogenated sulfonatedanthracene is its 40 17. Water 15. Sodium oleate 12.

An 8% concentration in naphtha is recommended. After being depleted of moisture, the solution re-absorbs it, but considerable agitation is required.

Sultonated hydrogenated anthracene--- Naplitha Oleic acid Water Potassium oleate Mono-butyl-ether of ethylene glycol CIOCIUIUI Per cent 5n This formula absorbs moisture very readily and its concentration in the naphtha solution Per cent Per cent 14.

is not critical. A 10% concentration isrecommended.

. Per cent ()leic acid 25 Nap 25 Pure mahogany sodium sulfonate 50 This material re-absorbs the moisture readily and can be used in any cleaning solvent suitable for dry cleaning in almost any proportions. A recommended concentration is 6%.

Per cent Oleic acid 3.). 3 Naphflm I. 35. 3 Cyclohexanol I 17. 6 Potassium hydroxide 5. 3 Water 3. 5 Triethanolamine 3. O

A 6% solutionis suitable for absorbing th usually desirable amounts of moisture.

Per cent Oleic acid .."3( 0 Naphtha 4o. 0 Butyl ethylene glycol mono ethyl ether 15.0 lclassium hydroxide 5. 0 Water. 5. 0 A 6% solution is suitable for absorbing the usually desirable amounts of moisture.

" of the cleaning process to insure best results or would be usable only where this control was available.

Of the various formulae provided, No. 6 is the preferred and recommended one because it possesses all of the requisite properties previously discussed, can be used with all of the types of cleaning solvents at present employed for dry cleaning, can be used safely and successfully on a commercial scale with out supervision of the cleaning process by skilled chemists, and can be used successfully on all types of fabrics adapted to be cleaned by this general process.

Moreover, formula No. 6 may be used in most dry cleaning plants as at present constituted without any substantial changes of equipment or material changes in handling and routing the fabrics through the plant except as herein specified.

Formulae Nos. 7 and 8 are characterized.

by very ready absorption of moisture and are suitable for use for fabric cleaning purposes without the exercise of an undue amount of chemical control. These formulae are characterized byv the use of partially saponified oleic acid and a material or reagent mutually miscible with oil and water. This reagent may be termed an absorption assistant. Cyclohexanol is the absorption assistant .of formula No. 7 and butyl ethylene glycol mono ethyl ether of formula No. 8. Other mutually miscible materials which may be used as absorption assistants, (though with varying degrees of safety on dyed fabrics), comprise butyl acetate, isopropyl alcohol, ethyl alcohol, di-acetone alcohol, ethylene glycol mono ethyl ether acetate, and diethylene glycol mono butyl ether. Absorption assistants which tend to be taken up by the fabrics must be periodically replenished.

In regard to these formulae Nos. 7 and 8, it must be noted that the presence of free fatty acid is desirable to render a fatty acid soap truly soluble in the cleaning solvent in the presence of moisture and that the absorption assistants augment the power to take up I the required quantities of moisture rapidly and in the proper condition of dispersion.

This application is a continuation in part of my previous co-pending application Serial N 0. 492,611, which discloses the Water dispersing action of mahogany sulfonates and several of the other absorbefacients and one use of this dispersing action in the cleaning of fabrics. Mahogany sulfonates are the salts of mahogany acids which are formed in the oil layer or A layer in the refining of medicinal white oil and the like by the use of fuming sulfuric acid and/or sulfur trioxide. The United States Patent to Divine, No. 1,493,111, issued May 6. 1924, discloses mahogany sulphonic bodies suitable for the practice of this process. I

Great care must be used in employing this invention with chlorinated cleaning solvents to avoid the formation of harmful quantities of hydrochloric acid and therefore throughout this description the invention has been disclosed in relation to the equipment of an open, naphtha process plant, though it must be understood that other types of equipment and plants may be used with appropriate minor modifications well within the skill of the art.

All claims directed to the specific absorbefacients and their use, as Well as claims directed to the improvement of the appearance of silks and wools are being prosecuted in copending divisional applications.

Having described my invention, I desire tobe limited only by the ensuing claims:

1. In the dry cleaning art, the process which'comprises cleaning fabrics with a dry cleaning solvent of the type exemplified by a volatile hydrocarbon or carbon which is moisture absorbent by rea son of an absorbefacient dissolved therein and which contains an amount of moisture determined in relation to the weight and nature of the batch of fabrics being cleaned, but does not exceed the moisture tolerance of the fabrics. I

2. In the dry cleaning art, the process which comprises cleaning fabrics with a dr cleaning solvent of the type exemplified by a chlorinated hydro-.

volatile hydrocarbon or chlorinated hydrocarbon which is moisture absorbent by rea son of an absorbefacient dissolved therein and which contains an amount of moisture determined in relation to the weight and nature of the batch of fabrics being cleaned, but does not exceed the moisture tolerance of the fabrics, the moisture in the cleaning liquid being so finely dispersed that the liquid is substantially optically clear.

3. In the dry cleaning art, the fabric cleaning process which comprises preparing a moisture absorbent cleaning liquid by dissolving an absorbefacient in a dry cleaning solvent of the type exemplified by a volatile hydrocarbon or chlorinated hydrocarbon, charging the liquid so constituted with moisture each time a batch of fabrics is cleaned therein, the amount of the charge in each case determined in relation to the weight and nature of the fabrics constituting the specific batch, but in no case exceeding the moisture tolerance of the fabrics and treating the fabrics with the liquid so constituted to remove greasy soil and water soluble soil concurrently in one operation.

4. In the dry cleaning art, the fabric cleaning process which comprises preparing a moisture absorbent cleaning liquid by dissolvingan absorbefacient in a cleaning solvent of the type exemplified by a volatile hydrocarbon or chlorinated hydrocarbon, forming a substantially optically clear dispersion of moisture in the liquid so constituted each time a batch of fabrics is cleaned therein, the amount of the' charge in each case determined in relation to the weight and nature of the fabrics constituting the specific batch but in no case exceeding the moisture tolerance of the fabrics and treating the fabrics with the liquid so constituted to remove greasy soil and water soluble soil concurrently in one operation.

5. The process of cleaning successive batches of fabrics in a body of dry cleaning solvent of the type exemplified by a volatile hydrocarbon or chlorinated hydrocarbon, said process comprising rendering the cleaning solvent, moisture absorbent by dissolvingan absorbefacient thereinand cleaning the successive batches of fabrics in said body of solvent, the cleaning of each batch being accompanied by the charging of the cleaning solvent with an amount of moisture equal to between 5 and 30% of the weight of the fabrics constituting the specific batch, the exact amount of moisture depending upon the tolerance of the fabrics constituting the batch.

6. The process of cleaning successive batches of fabrics in. a body of dry cleaning solvent of a type exemplified by a volatile hydrocarbon or chlorinated hydrocarbon, said process comprising rendering the cleandissolving an absorbefacient therein and cleaning the the batch removes successive batches of fabrics in said body of solvent, the cleaning of each batch of fabrics being accompanied by the charging of the cleaning solvent with moisture, the amount of moisture in each instance, being within the limitation of the moisture tolerance of the particular batch, whereby the removal of from the solvent substantially the moisture content previously added.

In witness whereof, I hereunto subscribe my name.

WARREN T. REDDISH.

CERTIFICATE OF CORRECTION.

. Patent No. 1,911,289. May 30, 1933.

WARREN T. REDDISH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 98, for "or" read "of"; page 4, line )1, for "blending agent" read "absorbefacient"; and that the said Letters with these corrections therein that the same may conform to the record of the Patent should be read case in the Patent Office.

Signed and sealed this 15th day of August, A. D. 1933.

M. J. Moore.

(Seal) Acting Commissioner of Patents DISCLALMER 1,911,289.Warren T. Redd'ish, Cincinnati, Ohio. METHOD OF CLEANING FABRICS. Patent dated May 30, 1933. Disclaimer filed June 14, 1940, by the assignee, Emery Industries, Inc. Hereby enters this disclaimer of claims 1, 2, 5, and 6 of the patent.

[Ofiicial Gazette July 9, 1.940.] v 

